1. Field of the Invention
The present invention relates to a writing instrument having a mechanism for transforming rotation of the rear tubular member into axial displacement of a writing tip.
2. Background Information
In the prior art, the writing tip of a writing instrument, for example a ball-point pen can be extended or retracted in response to directions of rotation of a rear tubular member of the writing instrument. The writing instrument can be used when the writing tip extends outwards from a front tubular member of the writing instrument.
In mechanical pencils of prior art, after the writing tip is extended outward from a front tubular member of the pencil in response to rotation of a rear tubular member of the mechanical pencil, a lead advancing mechanism is activated by a knock operation so that a lead projects from the writing tip, and then the pencil can be used.
In ball-point pens of the prior art, there is the problem of the mechanism for transformation of rotation and axial displacement presenting a mechanically complicated structure. Also in mechanical pencils of the prior art, there is the problem that they not only need the mechanism for transformation of rotation and axial displacement but also need a lead advancing mechanism to be activated by a knock operation, thereby the construction becomes further complicated. Further they need both a rotation operation and knocking operation, thus they lack simplicity and costs are increased.
Accordingly, it is an object of the invention to provide a writing instrument which can solve the above problems and whose construction is simpler and convenient.
It is a further object of the invention to provide a mechanical pencil which can solve the above problems and whose operation is easy.
In order to solve the above problems, a writing instrument according to the present invention comprises a front tubular member; a front inner tubular member disposed within the front tubular member; a refill inserted into the front inner tubular member; and a driver mounted in the front tubular member and front inner tubular member. The driver is allowed to rotate but not displace axially relative to the front tubular member and front Inner tubular member. A rear tubular member is detachably connected to the driver but not allowed to rotate relative to the driver; and a rear inner tubular member is inserted in the driver. An inclined path is provided on either the front inner tubular member or the rear inner tubular member. The inclined path extends obliquely relative to an axial line of the writing instrument from a beginning end to a Terminal end; and a projection is provided on the other of either the front inner tubular member or the rear inner tubular member. The projection engages the inclined path. The rear inner tubular member and the driver interengage with each other by engagement between at least one axial groove and a corresponding projection so as to allow axial displacement but no rotation relative to the driver.
The inclined path can be narrower at the beginning end and the terminal end than the other portion thereof so that a user can clearly realize the beginning end or the terminal end is reached.
The inclined path can have a first inclined path and second inclined path extending on an opposite side of the first inclined path so that a beginning end of the first inclined path coincides with a beginning end of the second inclined path.
Alternatively, the inclined path can have a first inclined path and second inclined path following the first inclined path so that a terminal end of the first inclined path coincides with a beginning end of the second inclined path.
The beginning end of the inclined path may be in communication with a rear inner void space of the writing instrument.
The beginning end of the inclined path may also be in communication with a rear inner void space of the writing instrument through a closed slit.
The beginning end of the inclined path may be in communication with a rear inner void space of the writing instrument through a closed slit and an open slit.
Alternatively, an engaging member having the inclined path is provided, and a slot is formed in one of either the front inner tubular member or the rear inner tubular member and having substantially the same shape as the engaged plate. The engaging member is engaged with the slot.
The writing instrument may further comprise friction generating means provided between the front inner tubular member and the driver for generating friction between them.
Alternatively, the writing instrument may further comprise friction generating means provided between the front inner tubular member and the rear inner tubular member for generating friction between them.
Alternatively, the projection can bend in a radial direction so that it can engage the inclined path by its flexibility. At least one slit provided in the vicinity of the projection allows the projection to bend in a radial direction. Otherwise either the front inner tubular member or the rear inner tubular member on which the projection is provided may have a cut off on the opposite side of the projection so that the projection can pass through either the front inner tubular member or the rear inner tubular member to engage with the inclined path.
Further a mechanical pencil according to the present invention comprises; a front tubular member; a front inner tubular member disposed within the front tubular member; a lead advancing assembly inserted into the front inner tubular member; and a driver mounted in the front tubular member and front inner tubular member which allows rotation but not axial displacement, relative to the front tubular member and the front inner tubular member. A rear tubular member is detachably connected to the driver which is not allowed to rotate relative to the driver; and a rear inner tubular member is inserted in the driver to allow axial displacement but not rotation relative to the driver. An inclined path is provided on either the front inner tabular member or the rear inner tubular member. The inclined path extends obliquely relative to an axial line of the mechanical pencil from a beginning end to a terminal end; and a projection is provided on either of the front inner tubular member or the rear inner tubular member, which engages with the inclined path. Therefore the lead advancing assembly can advance toward the front inner tubular member and the front tubular member as the rear inner tubular member advances.
The lead advancing assembly includes a lead casing extending toward a rear inner portion of the mechanical pencil.
Alternatively, the lead advancing assembly includes a joint member extending toward a rear inner portion of the mechanical pencil and a rear peripheral wall of said joint member defines a lead storage compartment together with a peripheral wall of the rear inner tubular member.
Operation of the writing instruments according to the present invention is carried out as follows.
In Case of a Ball-Point Pen
If the rear tubular member is rotated, the rear inner tubular member and refill rotate together with the rear tubular member, making the projection advance from the beginning end of the inclined path along the inclined path, to make a writing tip of a refill advance. When the projection reaches the terminal end of the inclined path, the writing tip projects from an extreme point of the front tubular member. In this position, the pen can be used to write.
If the rear tubular member is rotated in a direction opposite to the above, the rear inner tubular member and refill rotation is reversed, making the projection of the rear inner tubular member retract from the terminal end along the inclined path making the writing tip of the refill retract into the extreme point of the front tubular member when the projection returns to the beginning end of the inclined path.
In Case of a Mechanical Pencil
If the rear tubular member is rotated, the rear inner tubular member and refill advance, making the writing tip (i.e. front pipe of a slider or tip of a lead) of a refill advance, making the writing tip project from an extreme point of the front tubular member when the projection reaches the terminal end of the inclined path.
If the inclined path has a first inclined path and second inclined path extending on an opposite side of the first inclined path so that the beginning end of said first inclined path coincides with the beginning end of said second inclined path, the projection moves from the beginning end to the terminal end along the first inclined path, making the writing tip (front pipe of a slider or tip of a lead) project to serve as a pencil. When the projection reaches the terminal end of the second inclined path, a chuck of a mechanical pencil can be maintained open to free a lead thereby the writing tip can be pushed into the front tubular member.
If the inclined path has first inclined path and second inclined path following the first inclined path so that the terminal end of the first inclined path coincides with the beginning end of the second inclined path, the writing tip is pushed out from an extreme point of the front tubular member when the projection reaches the terminal end from the beginning end along the first inclined path. Further, the projection can reciprocally move between the beginning end and the terminal end of the second inclined path, advancing a lead from the writing tip to serve as a pencil.
Other objects and advantages of the invention will become apparent from the following portion of this specification and from the accompanying drawings .